diff --git a/util/autovector.h b/util/autovector.h
index 1e6c4716b..7e33e5ca8 100644
--- a/util/autovector.h
+++ b/util/autovector.h
@@ -19,6 +19,12 @@ namespace ROCKSDB_NAMESPACE {
 template <class T, size_t kSize = 8>
 class autovector : public std::vector<T> {
   using std::vector<T>::vector;
+
+ public:
+  autovector() {
+    // Make sure the initial vector has space for kSize elements
+    std::vector<T>::reserve(kSize);
+  }
 };
 #else
 // A vector that leverages pre-allocated stack-based array to achieve better